FORECAST SUMMARY: Friday, June 2, 2023, through Monday, June 5, 2023

Ozone: 8-hour average Ozone concentrations will range between Moderate and USG Friday, with reading between Good and Moderate the rest of the period.

PM-2.5: 24-hour average Fine Particulate through the period should range Good to low Moderate.

...AIR QUALITY ACTION DAY ADVISORY FOR FRIDAY, JUNE 2nd...

THE ACTION DAY ADVISORY IS IN EFFECT FOR THE FOLLOWING MICHIGAN COUNTIES...

IN WEST and central MICHIGAN:

ALLEGAN... BARRY... BENZIE… berrien… BRANCH... CALHOUN... CASS… CLINTON... EATON... GRAND TRAVERSE... HILLSDALE... INGHAM... IONIA... JACKSON... KALAMAZOO... KENT... LEELANAU… MANISTEE… MUSKEGON... Oceana… ottawa… MASON… ST JOSEPH AND van buren COUNTIES

IN Southeast MICHIGAN:

GENESEE... LAPEER... LENAWEE... LIVINGSTON… MACOMB… MONROE… OAKLAND… ST. CLAIR… SHIAWASSEE... WASHTENAW AND WAYNE COUNTIES

FORECAST DISCUSSION:

Hot, dry conditions end the workweek, along with another day of increased ozone levels. Thursday resulted in two monitors reaching USG along the western lakeshore and another six in central and eastern portions of the state. Increased ozone is likely again today (Friday), and we have a Clean Air Action Day in place covering the southern half of lower Michigan, extending north along the western shoreline counties up to Traverse City.

For the rest of the forecast period, a weak front sinks northwest to southeast through the state Saturday. This boundary brings some clouds and small chances for precipitation, along with a surface and upper-level wind shift to the east/northeast. Cooler surface and upper-level temperatures also settle in later Saturday and more so Sunday. While warmer surface temperatures remain in place Saturday, we feel clouds, scattered precipitation and winds shifting in direction will hamper a significant increase in ozone. Therefore, we are not continuing the Clean Air Action Day into Saturday and are forecasting Moderate ozone. We will, however, keep track of conditions and if areas start increasing where we feel USG may be reached, the forecast will be updated to USG triggering EnviroFlash notification for individuals signed up to receive them.

Cooler temperatures settling in Sunday should keep ozone in the Good to low Moderate range. By Monday, another stronger front sinks south through the state. This boundary brings clouds and more of an airmass clean out, but the downfall is there isn’t much precipitation associated with it. While areas could use some rain, this system will bring in cleaner air with ozone levels expected to range from Good to low Moderate.

Fine particulate levels should see a bit of improvement during the weekend, especially in the southeast where readings have been Moderate all week. Reading through the weekend are expected to range Good to low Moderate.

EXTENDED FORECAST:

High pressure settles in from Canada later Monday into Tuesday. Cooler temperatures and northeasterly winds should keep pollution no higher than low Moderate.

Next Forecast update: Monday, June 5, 2023. Forecast Updated by Stephanie M. Hengesbach